The Nerus Modified Austin Healey Sprite MK.II

As we mentioned in our road test of the Nerus modified Mini (August 1963) the Nerus organisation concentrates mainly on cylinder head gas-flowing and polishing rather than complete conversions. This is done in three stages ranging from a mild increase of power to a quite considerable increase. However the Stage III head really needs to be accompanied by other tuning operations to achieve a really notable power output and in the case of the 1,000 c.c. Austin Healey Sprite we tested recently this is what Nerus had done. The cylinder head was the Stage III version with 10.5:1 compression ratio, larger inlet and exhaust valves, double valve springs and the usual port and combustion chamber shaping and polishing. The standard S.U. carburetters were replaced by two 1 1/2 in. S.U.s on a modified inlet manifold which incorporated a heat shield to deflect heat from the modified exhaust manifold which runs into a new down pipe. The total cost of this equipment is £70 15s. Fitting is extra but this particular kit is easy to fit as the work entailed is merely that of removing the old components and replacing the new, which should not take the amateur mechanic more than three or four hours to fit. This will operate well without changes to ignition settings but obviously careful adjustments will enable maximum power to be achieved. A Crypton electronic tune-up might be a good investment when fairly radical engine modifications have been made. Naturally more power would be achieved with a high-lift camshaft and although one is not included in this conversion three different camshaft grinds are available on an exchange basis costing from £8 to £11 10s.

The test car was a standard 1100 Sprite except for the conversion and apart from a deeper exhaust note and its Nerus badge it was indistinguishable from the normal model. Acceleration seemed to be improved quite considerably although as the figures in the data table indicate the test car was not a lot quicker against the stop watch than the standard 1100 model from a standing start and undoubtedly the improved torque in the middle of the rev range accounted for the good acceleration in the 40 to 60 m.p.h. range. The engine was no noisier than standard but in really heavy traffic the water temperature reached 200°C. and the engine occasionally fluffed or stalled. The engine will rev to 7,000 r.p.m. in the lower gears but performance figures do not benefit greatly from going to this figure and with gear changes made at 6,500 r.p.m. speeds in the gears are 32, 54 and 74 m.p.h. while the maximum speed on the flat is 96 m.p.h. A slight downhill run will see 100 m.p.h. come up and the rev counter is showing 6,800 r.p.m. at this speed.

The virtues and faults of the Sprite have been discussed many times in these columns so suffice it to say that the Nerus car follows the pattern, having good handling, a firm but not uncomfortable ride, dependable brakes, light steering, an acceptable gearbox, a rather cramped cockpit and a miniature boot. The 10 1/2 compression ratio requires 100 octane fuel and the Nerus car consumed this at the rate of 33.2 m.p.g. and required a negligible amount of oil. Details from Nerus Engineering Co., Rye, Sussex.—M. L. T.

Performance figures

Speed - Standard M.G. Midget Mk. II - Nerus Austin Healy Sprite Mk. II
0-30 m.p.h. - 4.85 sec. - 4.25 sec.
0-40 - 7.90 - 7.25
0-50 - 11.25 - 10.40
0-60 - 16.20 - 14.70
0-70 - 23.00 - 32.90
0-80 - x - 32.90

Standing start 1.4-mile - 20.10 sec. - 19.50 sec.

Speeds in gears
First (6,500 r.p.m.) - 32 m.p.h. - 32 m.p.h.
Second - 54 - 54
Third - 74 - 74
Top - 92 - 96

(N.B.—The figures quoted for the standard model are for the M.G. Midget tested in our April 1963 issue)